Why do you need Comcast AND Satellite AND an antenna? Comcast carries all your local channels already, so you shouldn't need the antenna at all.
You can usually get your local channels from Dish as well, and Dish carries the same channels as Comcast, so I really don't understand why you need all 3.
But...since that's your setup, this is what you'll do.
First, does your TV have AV inputs? These are the yellow (video), red (audio) and white (audio) jacks on the back or sometimes the front of the TV. If your TV is older it may just have yellow and white (this means your TV only does mono-sound, not stereo.) If the answer is YES, then you will use a set of AV cables (yellow, red, white) to connect each box to the TV.
If your TV is newer, it may have multiple sets of inputs, so you can connect each box to a separate input. Then just use the TV remote to change between inputs (also called axillary, or video sources)
If your TV only has 1 set of AV inputs, or doesn't have enough inputs, you can get a AV switch from the store for about $20. This will let you connect up to 4 different devices to a single input on your TV. Leave the TV's channel set to the AUX/Video then just use the buttons on the switch to choose which device (Cable, Satellite, Antenna box) you're going to use.
If your TV doesn't have these AV ports at all, and only has the coax cable port, you can still get an AV switch from the store. Just make sure you get the one that has coax-out, instead of AV-out. Then use a set of AV cables to connect each box to the switch, and a coax cable to connect the switch to your TV. Set the TV's channel to whatever the switch uses (usually 3 or 4). Use the switch to choose which box you're going to watch (cable, satellite, antenna) and the appropriate remote to change the channel.